JP2009031281A - Core spray sparger t box clamp assembly and its using method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seamless clamp for a universal core spray sparger T box advantageous for remote repairing. <P>SOLUTION: The core spray sparger T box clamp assembly 100 comprises an anchor plate formed approximately in line with a cover plate of the sparger T box 15, a clamp equipped with a latch to be engaged with this anchor plate to be coupled and fixed to the T box 15, a sparger pipe support mounted on at least one sparger pipe 10 adjacent to the T box 15, firmly coupled to the anchor plate with at least one dimension, and a tube support plate extendably mounted on the anchor plate so as to abut on the cover plate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates generally to boiling water light water reactors (BWRs) and assemblies and methods for reinforcing piping for coolant spraying within such reactors.

  In general, a BWR includes a core surrounded by a shroud and a shroud support structure. Typically, piping passes through this shroud and delivers emergency cooling water to the core in the event of an emergency including coolant loss or for other reasons when the core becomes unavailable.

  As shown in FIG. 1, such piping includes core spray piping 10 and a sparger that are used to pump cooling water to the core. The core spray cooling water is usually supplied to the core region through a sparger T box 15 that penetrates the shroud wall. The distal end portion of the T box 15 is inside the shroud, and the proximal end portion extends outside the shroud.

  Typically, a sparger T box intersects two sparger pipes 10 to form a “T” shaped pipe. The sparger pipe 10 is usually welded to the sparger T box 15. The tip of the T box 15 may be covered with a flat cover plate 20 welded to the T box 15. Although only the lower sparger T box 15 is shown in FIG. 1, there is usually an upper sparger T box as well, and the upper configuration is substantially the same as the lower sparger T box. Usually, the lower T box intersects the sparger pipe 10 with a vertical displacement at the center so that the sparger pipe 10 meshes symmetrically with the upper and lower halves of the lower T box 15. Due to other structural arrangements, the upper sparger T box may not intersect the sparger pipe 10 with a longitudinal displacement in the center, and therefore the sparger pipe 10 does not mesh symmetrically with the upper sparger T box. Also good.

  The cover plate welded portion 25 and the sparger pipe welded portion 26 are likely to be cracked by water whose chemical properties are variously changed at high temperature and pressure flowing around the T box 15. As a result, the opportunity to repair and inspect inside the BWR for damage that occurs to the welds 25 and 26 will be limited to the scheduled shutdown of the power plant for refueling and repair. Such periodic shutdowns are usually performed at intervals of several months, so that the components inside the core, including welds 25 and 26, remain intact for a long time until inspection and / or repairs are performed. Must be maintained.

  In addition, the operating conditions of the BWR core include high levels of radioactivity due to fission occurring in the fuel rods. Radioactivity, particularly the neutron flux generated in the core of an operating reactor, degrades the material strength and elasticity of the core components over time. Accordingly, the components inside the core including the welds 25 and 26 are likely to be prematurely embrittled and cracked by such radiation exposure. Accordingly, vibrations induced by flow, long operating cycles and harsh water conditions are combined with radiation, causing cracks in the welds 25 and 26, particularly due to intergranular stress corrosion cracking. If the cracks in the welds 25 and 26 spread out in the circumferential direction enough to completely separate either the cover plate 20 or the sparger pipe 10 from the sparger T box 15, an uncontrolled cooling water leak may occur.

  What further exacerbates the unstable characteristics of the sparger T-box welds 25 and 26 is the fact that they are located inside the shroud among other components. Even during repairs, workers can only operate the sparger T-box 15 inside the shroud from a remote location, and the cost of repairing the location of the T-box weld is increased and other components must be removed. And the danger of workers increases.

  Conventional sparger T-box repairs and clamps may use a clamping mechanism to relieve stress on the welds 25 and 26 and ensure dual safety in the event of a weld failure. is there. The sparger T box 15 may have various physical configurations based on a specific plant installation history and repair history. Conventional repair mechanisms are generally configured only for a single sparger T box in a particular BWR and are not compatible with other sparger T boxes of other BWRs.

  Embodiments relate to the repair of core spray sparger T-boxes, and more particularly to methods of using universal core spray sparger T-box seamless clamps and universal core spray sparger T-box seamless clamps that are convenient for remote operation. Embodiment clamps may be secured to a variety of upper and lower sparger T box configurations without welding. Embodiment clamps may be configured to engage simultaneously with a sparger T-box in multiple dimensions to allow for a free fit. Furthermore, the embodiment clamps can be operated, installed or removed by working only on the front surface of the embodiment clamps, thus potentially reducing the difficulty and cost of repairing the embodiment clamps remotely. Reduce.

  The embodiments will become more apparent from the detailed description of the embodiments with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals in the drawings. The drawings are presented for purposes of illustration only and therefore do not limit the embodiments.

  FIGS. 2 and 3 show core spray sparger T box clamp assemblies 100 and 200 that are respectively attached to the lower sparger T box 15 and the upper sparger T box 16 and may be attached to the sparger pipe 10 on both sides of each sparger T box. FIG. 6 is an isometric view illustrating the embodiment. The clamp assemblies 100 and 200 of this embodiment may reinforce the welds 25 and 26 (shown in FIG. 1) between the T box, the cover plate, and the sparger pipe to increase safety. The clamp assemblies 100 and 200 of this embodiment hold the pipe 10 and the cover plate 20 (shown in FIG. 1) against the sparger T-boxes 15 and 16, and thereby welds 25 and 26 (shown in FIG. 1). And the leakage of coolant from the welds 25 and 26 may be prevented or minimized if cracks occur around the entire periphery.

  In the following, embodiments will be described with respect to the lower core spray sparger T box clamp assembly 100. Since the upper clamp assembly 200 shares features with the lower clamp assembly 100, redundant description is omitted.

  FIG. 4 is an exploded view showing the clamp assembly 100 of the embodiment of FIG. As shown in FIG. 4, the clamp assembly 100 of this embodiment includes an anchor plate 110 between two sparger pipe supports 115 and 116. The anchor plate 110 may be in front of the sparger T box 15 (as shown in FIG. 2) and is substantially aligned with the sparger T box 15 and the cover plate 20 (shown in FIG. 1), and the sparger T box and cover. The plates may be shaped to cover and / or overlap them. The sparger pipe supports 115 and 116 are engaged with the left and right sparger pipes 10 on both sides of the sparger T box 15 via, for example, the inner T bolt 121 and the outer T bolt 122 to support the sparger pipe. Anchor plate 110 and sparger pipe supports 115 and 116 may be positioned in any relative position to accommodate various sparger T-box configurations. For example, the upper sparger T box may be displaced in the vertical direction from the sparger pipe 10, in which case the anchor plate 110 and the sparger pipe support 115 are similarly displaced in order to accommodate the upper sparger T box. May be.

  The anchor plate 110 and the sparger pipe supports 115 and 116 are joined by a dovetail. The dovetail causes the sparger pipe supports 115 and 116 to translate axially with respect to the anchor plate, but prevents lateral translation along the length of the pipe supports 115 and 116. In this manner, the anchor plate 110 and the pipe supports 115 and 116 may be independently fixed to the sparger T box and the sparger pipe. Further, the dovetail allows the anchor plate 110 and the pipe supports 115 and 116 to be installed with different amounts of misalignment in the axial direction to accommodate different sparger T-box configurations and pipe configurations.

  First, in order to attach the clamp of the embodiment to the sparger pipe, an example of a structure for attaching the sparger pipe supports 115 and 116 to the sparger pipe 10 will be described.

  In one embodiment, the sparger pipe supports 115 and 116 may be attached to the sparger pipe 10 by inner T bolts 121 and outer T bolts 122. The T bolts 121 and 122 may be fixed to the supports 115 and 116 by T bolt nuts 131 and 132. The T bolts 121 and 122 may pass through an opening 50 (shown in FIG. 12) formed in the sparger pipe 10 by, for example, electric discharge machining. The threaded end of each T-bolt 121 and 122 may penetrate the pipe support 116. To prevent coolant leakage through the opening 50, the sealing collars 141 and 142 may contact the sparger pipe around the opening 50. The T-bolt nuts 131 and 132 may be screwed onto the screw ends of the corresponding T-bolts 121 and 122. In order to slide the T-bolts into the corresponding openings 50, the head of each T-bolt 121 and 122 may have a key shape, for example, a rectangular shape. The T-bolt inserted into the opening 50 may be rotated and thereby locked into the sparger pipe 10.

  The sealing collars 141 and 142 may be disposed on the T bolts 121 and 122 such that the collars 141 and 142 are pressed against the curved outer surface of the sparger pipe 10 as the T bolt nuts 131 and 132 are tightened. The sparger pipe supports 115 and 116 are provided to allow the T bolts 121 and 122, the T bolt nuts 131 and 132, and the sealing collars 141 and 142 to pass through and / or abut the pipe supports 115 and 116. You may have a recessed part and a hole.

  In order to make the T-bolt nuts 131 and 132 rotatable only in one direction, the ratchet spring 125 may be inserted into adjacent slots of the sparger pipe supports 115 and 116. For example, the ratchet spring 125 may only allow the T-bolt nuts 131 and 132 to be tightened. The ratchet spring 125 may be key-shaped to allow disengagement from the T-bolt nuts 131 and 132 and to allow the nuts 131 and 132 to rotate in both directions. For example, the ratchet spring 125 may be key shaped to disengage the sparger pipe supports 115 and 116 and allow removal.

  The embodiment and the structural example for attaching the clamp of the embodiment to the sparger pipe are described as the sparger pipes 115 and 116 being joined to the sparger pipe 10 via the T bolt 121, the T bolt nut 131 and the sealing collar 141. However, other fixing structures can be used in combination with this embodiment. For example, as is well known to those skilled in the art, the sparger pipe support may be attached to the sparger pipe by welding and / or gripping fasteners around the sparger pipe.

  Secondly, an example of a unique clamp for fixing the clamp assembly of the embodiment to a sparger T box having various configurations will be described.

  The embodiment clamp assembly includes a dovetail that allows axial movement between the anchor plate 110 and the sparger pipe supports 115 and 116 so that the anchor plate 110 is independently clamped to the sparger T box. . The sparger T-box may have various configurations and front plate structures, and the embodiment has a unique universal clamping mechanism that can be operated from the front mounted on the sparger T-box with a wide variety of front features and dimensional characteristics. provide.

  As shown in FIG. 4, the clamp assembly of this embodiment includes a center post 151, a ratchet nut 152, a slider wedge 153, a ratchet nut lock 154, a pair of slide latches 155 and / or four flat head screws 156. With these structures, the clamp of this embodiment can be securely and removably engaged with various sparger T-boxes.

  5 and 6 show the latch structure described in FIG. 6 is a cross-sectional view taken along line VV in FIG. As shown in FIG. 6, the anchor plate 110 may have a rectangular recessed area 111 that receives the rectangular end of the central column 151. Due to the rectangular shape, it is impossible for the central column 151 to rotate in the recessed area 111. However, the recessed area 111 may translate the central strut 151 within the recessed area 111, thereby repositioning the center of the anchor plate 110 to accommodate the irregular T-box shape. Such correspondence will be described in more detail below.

  The ratchet nut 152 and the ratchet nut lock 154 are disposed at the end of the center post 151 opposite to the rectangular end. The outer surface of the ratchet nut 152 engages with the inner surface of the ratchet nut lock 154 so that the ratchet nut 152 rotates only in one direction. As the ratchet nut 152 rotates, the inner surface of the ratchet nut engages with the thread at the end of the central post 151, thereby pulling the ratchet nut 152 along the central post 151 in the axial direction. For example, the ratchet nut lock 154 may rotate the ratchet nut 151 only in a direction corresponding to the direction in which the ratchet nut 151 is fastened to the central column 151 downward in the axial direction.

  Ratchet nut lock 154 may include a release 158. Release 158 is a hole into which a tool for removing ratchet nut lock 154 from ratchet nut 152 can be inserted to allow rotation of ratchet nut 152 in any direction including tightening and loosening along central post 151. Also good.

  The slider wedge 153 is inside the ratchet nut 152 but is not completely restrained by the ratchet nut 152. The central column 151 passes through the slider wedge 153. The slider wedge 153 is not firmly attached to the ratchet nut 152, but the slider wedge 153 and the ratchet nut lock 154 are firmly and firmly fixed together by, for example, a flat head screw 156 that passes through the ratchet nut lock 154 and the slider wedge 153. The The slider wedge 153 and the ratchet nut lock 154 may be fixedly held by a slide latch 155 that meshes with a fixed sparger T box. Thus, the ratchet nut 152 may rotate and move axially along the central post 151. However, the ratchet nut lock 154 and the slider wedge 153 do not rotate with the ratchet nut 152, and translate with the ratchet nut 152 only in the axial direction.

  FIG. 7 is an isometric view showing a slider wedge 153 that can be used in the embodiment. FIG. 8 is an isometric view showing a slide latch 155 that can be used in the embodiment. As shown in FIG. 8, the slide latch 155 may have a bent end 165 and a conical end 166. The bent end 165 may mesh with the bent inner surface 163 of the slider wedge 153 shown in FIG. As shown in FIG. 6, the bent end 165 may fit into the bent inner surface 163 to prevent the slider wedge 153 from rotating unless the slide latch 155 can rotate. As the slider wedge 153 is translated axially along the central post 151, the slide latch 155 may be pulled radially inward by the engagement of the bent inner surface 163 and the bent end 165. The slider wedge 153 does not move the slide latch 155 further inwardly in the radial direction because the conical end 166 is held stationary and / or further movement of the end 166 in the radial direction is prevented. The wedge 153 and the ratchet nut 152 cannot be tightened any more along the central post 151.

  FIG. 9 shows the anchor plate 110 in more detail, including a T-shaped slot 112 along the face of the anchor plate 110. The slot 112 secures the slide latch 155 together with the anchor plate 110 and prevents rotation of the slide latch 155, the ratchet nut lock 154 and / or the slider wedge 153 with which the ratchet nut lock 154 is engaged. However, the slot 112 moves the slide latch 155 radially inward and outward while the slide latch 155 is tightened against the sparger T box. Further, the direction of the slot 112 may coincide with the orientation of the recessed areas 111 (shown in FIGS. 5 and 6) on both sides of the anchor plate 110. As described above, the central column 151 may translate only in the direction corresponding to the direction of the slot 112 and the direction of the slide latch 155 with respect to the recessed region 111. Therefore, if the anchor plate 110 and the central post 151 are not initially positioned at the central position between the outside of the sparger T box, the central post is moved to the central position between the slide latches 155 by the clamping force from the slide latch 155. Can translate. Thus, the clamp assembly of the present embodiment can cope with various different or non-uniform outer shapes of the sparger T box without being mounted non-uniformly on the sparger T box.

  FIG. 10 shows an embodiment of the same clamp assembly as in FIGS. 5 and 6, but the ratchet nut 152, ratchet nut lock 154 and slider wedge 153 are advanced further axially along the central post 151. FIG. . As shown in FIG. 10, the slide latch 155 is pulled inward in the radial direction by the axial translation of the slider wedge 153.

  The conical end 166 of the slide latch 155 may engage the hole 60 (shown in FIG. 12) of the sparger T box 15. The hole 60 may be formed by any known method including, for example, electric discharge machining. When the conical end 166 is fully inserted into the bore 60, the latch does not translate further radially inward and the tightening of the ratchet nut bolt is prevented or restrained.

  The example of the clamp for fixing the clamp assembly of the embodiment to the sparger T box having various configurations has been described. However, it is possible to deviate from these examples by a normal experiment to cope with other configurations. Will be apparent to those skilled in the art. For example, the shape of the end 166 of the slide latch 155 need not be conical or need to engage the T-box in a single region. Any equivalent structure that engages the slide latch 155 with the sparger T box may be substituted. Similarly, no screws need be used to secure the slider wedge to the ratchet nut lock, and no T-shaped slot is required to prevent rotation of the slide latch. Any structure for engaging the slider wedge, ratchet nut lock and slide latch may be implemented.

  These structural examples provide one embodiment of a clamp assembly that can be secured to the body of a sparger T-box with a variety of configurations, and show how installation and removal can be accomplished with a single nut structure operable from the front.

  Thirdly, the clamp assembly of the present embodiment further includes a structure that abuts the cover plate 20 to support the welded portion 25 and prevent coolant leakage that may occur when the welded portion 25 fails. But you can.

  As shown in FIG. 4, the clamp assembly of this embodiment may include a support plate 160, a support plate bolt 161, and a latch spring 162. The support plate 160 may be deflected so as to contact the cover plate 20, and the cover plate 20 may be fixed when a failure occurs in the welded portion 25. The support plate 160 may be coupled to the anchor plate 110 by a support plate bolt 161 that passes through a screw hole 113 (shown in FIG. 9) of the anchor plate 110. The support plate bolt 161 may rotate to move the support plate 160 toward the T box cover plate 20. The latch spring 162 may lock the rotational position of the support plate bolt 161 to ensure that the force applied to the cover plate 20 by the support plate 160 does not decrease during long periods of operation. The latch springs 162 may be fitted into corresponding slots in the surface of the anchor plate 110 and disengaged by a key structure that removes the latch springs 162 from the bolts 161 to rotate the bolts 161 in both directions. Also good.

  An example of a method for operating the core spray sparger T box clamp assembly will be described with reference to FIGS. FIG. 11 is a flowchart showing an example of a method of operating the core spray sparger T box clamp. As shown in FIG. 11, in the operation step S10, slots and holes may be formed in the existing sparger pipe and sparger T box. The slots and holes may be arranged in any shape to engage and clamp the clamp assembly to the sparger pipe and sparger T box. For example, the slot may be machined into a sparger pipe and the hole may be machined on both sides of a sparger T box. Any known process for forming those holes and slots, including electrical discharge machining, may be used.

  FIG. 12 shows an example of the process S10 in a state where the slot 50 and the hole 60 are respectively processed in the sparger pipe 10 and the sparger T box 15.

  As shown in step S20, the anchor plate may be clamped to the sparger T box. Such clamping may be performed by simple rotational clamping in the plane of the clamping mechanism and may accommodate a variety of sparger T-box configurations. The clamp may also position the clamp assembly in the middle between the clamp areas of the sparger T box.

  As shown in step S30, the sparger pipe support may be attached to the sparger pipe so as to fix the sparger pipe support to the sparger pipe. The support body may fix the sparger pipe only in the lateral direction parallel to the support body. The anchoring of the sparger pipe support may include tightening the sparger pipe support only at the surface of the sparger support.

  The clamp assembly may be secured to the sparger T box cover by clamping in the plane of the anchor plate. Thus, all embodiments of the method require only manipulation on the face of the clamp assembly in order to operate the clamp assembly. However, the method of the present embodiment may allow operation on other sides and / or sides of the clamp assembly.

  As shown in step S40, the support plate may then be deflected to contact the cover plate of the sparger T box.

  While embodiments and methods have been described above, it will be appreciated by those skilled in the art that examples of these embodiments and methods may be modified through routine experimentation without further inventive activity. Variations are not to be regarded as a departure from the spirit of the embodiments of the invention, and all variations that would be apparent to a person skilled in the art are intended to be included within the scope of the claims.

It is the figure which showed the conventional BWR sparger pipe in the state which the lower sparger T box has meshed with the sparger pipe. FIG. 5 is an isometric view showing the core spray sparger T box clamp assembly of the embodiment installed in the lower sparger T box and the upper sparger T box, respectively. FIG. 5 is an isometric view showing the core spray sparger T box clamp assembly of the embodiment installed in the lower sparger T box and the upper sparger T box, respectively. It is the exploded view which showed one Embodiment of the sparger T box clamp assembly. It is the front view which showed the anchor plate and the clamp structure. It is the cross-sectional view which showed one Embodiment of the anchor plate and clamp structure which can be used in the clamp assembly of embodiment. It is the isometric view which showed an example of the slider wedge which can be used in the clamp of embodiment. It is the isometric view which showed an example of the slide latch which can be used in the clamp of embodiment. It is the isometric view which showed an example of the anchor plate which can be used in the clamp of embodiment. It is the front cross-sectional view which showed the clamp of embodiment in the installed structure. 6 is a flow chart illustrating an embodiment of a method of using a core spray sparger T box clamp assembly. FIG. 5 shows a BWR sparger pipe and T box after forming slots and holes according to the method of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Sparger pipe, 15, 16 ... Sparger T box, 20 ... Cover plate, 25, 26 ... Welded part, 100 ... Core spray sparger T box clamp assembly, 110 ... Anchor plate, 115, 116 ... Sparger pipe support, 121 ... Inside T-bolt, 122 ... Outside T-bolt, 131, 132 ... T-bolt nut, 141, 142 ... Sealing collar, 151 ... Center post, 152 ... Ratchet nut, 153 ... Slider wedge, 154 ... Ratchet nut lock, 155 ... Slide latch, 160 ... support plate, 200 ... core spray sparger T box clamp assembly

Claims (10)

In the core spray sparger T box clamp assembly 100 of the sparger T box 15 in the nuclear reactor,
An anchor plate 110 formed to be substantially aligned with the cover plate 20 of the T box 15;
A clamp comprising a plurality of latches 155 that engage the anchor plate 110 and configured to couple and secure the anchor plate 110 to the T-box via the latch 155;
At least one sparger pipe support 115 configured to be attached to at least one sparger pipe 10 adjacent to the T box and rigidly coupled to the anchor plate 110 in at least one dimension;
A clamp assembly comprising: a support plate 160 that is detachably attached to the anchor plate 110 and configured to contact the cover plate of the T box. The clamp further includes a rotatable extending portion on a front surface of the clamp assembly 100, and the rotatable extending portion causes the clamp to move to the T box via the latch 155 when rotated. The clamp assembly according to claim 1, wherein the clamp assembly is configured to be tightened. The clamp assembly according to claim 1, wherein the clamp further includes a ratchet nut 152, a ratchet nut lock 154, a slider wedge 153, and a center post 151. The central column 151 penetrates the anchor plate 110, the ratchet nut 152, the ratchet nut lock 154, and the slider wedge 153 concentrically, and the slider wedge 153 is nested in the ratchet nut 152. The clamp assembly according to claim 3, wherein the ratchet nut (152) is telescopically housed in the ratchet nut lock (154). The ratchet nut lock 154 is rigidly coupled to the slider wedge 153, and the ratchet nut lock 154 engages the ratchet nut 152 to allow rotation of the ratchet nut in only one direction. The clamp assembly according to claim 3. The clamp assembly according to claim 1, wherein the latch (144) is engaged with both sides of the T box (15) to position the clamp and the anchor plate (110) in the center of the both sides. The clamp assembly according to claim 1, wherein the anchor plate (110) and the sparger pipe support (115) are firmly coupled only in two mutually perpendicular directions. The clamp assembly according to claim 7, wherein the anchor plate (110) and the sparger pipe support body (115) are coupled by a dovetail. The clamp assembly of claim 1, wherein the sparger pipe support includes at least one T-bolt 121, at least one T-bolt nut 131, and at least one sealing collar 141. The sparger pipe support is coupled to the sparger pipe 10 by the T bolt 121, the T bolt nut 131, and the sealing collar 141, and the T bolt penetrates the sparger pipe support into the sparger pipe 10. The clamp assembly according to claim 9, wherein the clamp assembly extends.

Images